Field of the Invention
This invention relates generally to suspension systems and more particularly to a head suspension assembly for a data storage system.
Description of the Prior Art
Direct access storage devices (DASD), or disk drives, store information on concentric tracks of a rotatable magnetic recording disk. A magnetic head or transducer element is moved from track to track to read and record the desired information. Typically, the magnetic head is positioned on an air bearing slider which flies above the surface of the disk as the disk rotates. In some recently proposed disk drives, the slider (or carrier) rides on a liquid film or bearing on the disk. A head suspension assembly connects the slider to a rotary or linear actuator. The suspension provides support for the slider and allows the slider to gimbal in order to adjust its orientation as appropriate.
The head suspension assembly typically comprises a load beam attached to an actuator arm, a flexible member (known as a flexure) attached to the load beam, and a slider attached to the flexure. Examples of these suspension systems include U.S. Pat. No. 3,931,641 by Watrous; U.S. Pat. No. 4,167,765 by Watrous; U.S. Pat. No. 4,261,024 by Desserre; U.S. Pat. No. 4,807,054 by Sorensen, et al.; U.S. Pat. No. 4,860,137 by Shtipelman; U.S. Pat. No. 4,868,694 by Hagen; U.S. Pat. No. 4,884,154 by Onodera, et al.; U.S. Pat. No. 4,996,616 by Aoyagi, et al.; German patent DE 1909245; European patent application 90314434.3 by Kahn; and IBM Technical Disclosure Bulletin, Vol. 32, No. 3A, Aug. 19, 1989.
Disk drives have become smaller in size while at the same time their data storage capacity has greatly increased. The data recording density of the disks has gone up dramatically and the data tracks have become smaller and closer together. The recording heads and sliders have also decreased in size. These lighter weight heads and sliders require a more flexible suspension to support them. The large suspensions used in the older disk drives are too stiff to allow the new smaller sliders to adjust their position. While the suspensions must be flexible in the vertical direction as well as allow pitch and roll of the slider, the suspension must also be rigid in the horizontal or lateral direction in order to prevent unwanted side to side movement.
Traditionally, this problem was solved by using thinner and thinner suspension members with a proportionally larger ratio of width to thickness. However, the lower limits of thickness to which materials can be milled is being approached. Steel can be milled accurately to a thickness of 0.025 mm. For sake of comparison, a piece of paper is 0.1 mm thick. Below 0.025 mm in thickness, the irregularities in the grain structure of the steel cause great variations in the thickness and make the material unsuitable for use in suspensions.
What is needed is a suspension system which can provide the desired flexibility in the vertical direction for the smaller heads and sliders, while at the same time maintaining adequate rigidity to prevent bending in the horizontal direction.